Upgrade your existing refractometer with the Aquarium Elements LED Upgrade Replacement, an innovative prism cover designed to provide consistent, built-in illumination. This essential accessory eliminates the hassle of searching for an external light source, ensuring you always have optimal lighting for accurate salinity readings in your saltwater aquarium. Installation is quick and straightforward, taking only a minute to replace your current cover by simply loosening a set screw, sliding off the old, and sliding on the new. Compatible with BRS refractometers and many other brands, this LED cover is designed for ease of use. It features an onboard battery that is built to last for years, providing reliable performance without frequent replacements. The suggested refractometer body diameter for optimal fit is 0.965 inches (24.6mm). This LED upgrade is perfect for any reef keeper seeking to enhance the precision and convenience of their salinity testing routine. By guaranteeing a proper light source for every reading, it helps maintain stable water parameters, contributing to a healthier and more thriving reef environment. Ensure consistent and reliable measurements with this simple yet effective enhancement.